Inmates at jails in Indianapolis, Baltimore, St. Louis and Philadelphia face the nation’s highest levels of sexual abuse at the hands of guards, according to a new federal report based on surveys of inmates at U.S. jails and prisons.The report by the U.S. Department of Justice found that the Marion County Jail’s inmate-intake center in Indianapolis had a 7.7 percent rate of staff sexual misconduct involving inmates — the nation’s highest for jails — and well above the average 1.8 percent sex abuse rate among all jails surveyed.